JPS6034718A - Collecting apparatus of fine particle - Google Patents

Abstract

PURPOSE:To prevent the formation of a large temp. difference at a trap part by firing collected fine particles after the warmth of the trap is confirmed. CONSTITUTION:The opening of a suction throttle valve 12, the pressure on the suction side of a Diesel engine 10, the water temp. of the engine, and the load of the engine are detected respectively by an opening sensor 52, a pressure sensor 54, a temp. sensor 56, and a load sensor 58. And the collected fine particles are fired after the warmth of a trap 20 is confirmed. In this way, the formation of a large temp. difference at the trap part 20 can be prevented, and the damage and failure of the trap is avoided. Accordingly the depend ability on the apparatus is increased.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a particulate collection device that collects particulates contained in the exhaust gas of an engine, and particularly to a particulate collection device in which particulates collected in a filter are ignited and burned by a heater. This invention relates to a particulate collection device that allows the filter to be reused.

[Technology 1'] Diesel engines may contain particulates in their exhaust gas. These fine particles are generated due to incomplete combustion of fuel and are made of carbon, hydrocarbons, metals, etc.
Flammable.

When the exhaust gas containing the fine particles is directly discharged from the vehicle, the exhaust gas becomes black smoke-like and is accompanied by an unpleasant odor.

Therefore, it is inconvenient to discharge such exhaust gas directly from the engine in terms of maintaining a clean and comfortable environment.

In this type of device, the particulates contained in the exhaust gas are collected by a filter and the exhaust gas is purified before a predetermined amount of particulates are collected and accumulated in the filter and the output of the engine is reduced. At a predetermined time, the most upstream collected particles are ignited by the heater. The ignited particulates act as a spark, and the collected particulates downstream self-combust due to the oxygen in the exhaust gas. This combustion completes the regeneration of the filter, making it possible to collect particulates again.

In conventional devices of this type, when a predetermined amount of particles are collected and accumulated in the filter and a predetermined time is reached before the engine output decreases, the captured particles are immediately ignited by the heater and regeneration of the filter begins. was.

Therefore, in the prior art, combustion of particulates collected by the filter may start before the trap is warmed up, and thermal stress is generated in the trap portion. As a result, there has been a problem that the trap is damaged or its durability is reduced.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its object is to provide a particulate collection device that does not cause damage to the trap or decrease in its durability.

[Summary of the invention]! 2. [In order to achieve objective 1, the present invention provides a trap that includes a filter that collects particulates contained in engine exhaust gas and a heater that ignites the particulates collected by the filter;
The present invention is characterized in that it includes temperature detection means for detecting the temperature of the trap, and a power supply circuit that starts supplying ignition current to the heater when the temperature of the trap exceeds a predetermined value.

[Embodiments of the Invention] Examples of the apparatus according to the present invention will be described below based on the drawings.

FIG. 1 shows the overall configuration of the apparatus of this embodiment.

In the figure, an intake throttle valve 12 is provided on the intake side of a diesel engine 10, and the intake throttle valve 12 is driven by an actuator 14. Furthermore, a fuel injection valve 1 that controls the fuel injection amount for the diesel engine IO
6, and an EG that recirculates the exhaust gas to the intake side.
An R valve 18 is provided between the intake and exhaust. A trap 20 is provided in the exhaust path of the diesel engine lO. The casing 22 of this trap 20 is formed into a columnar shape with a substantially elliptical cross section narrowed at both ends. has been done. A J-ma filter 24 is placed within this casing 22. The filter 24 can collect particulates contained in the exhaust gas of the diesel engine lO, and the particulates gradually move from the exhaust inlet to the outlet of the filter 24.
Multiply.

Further, within the casing 22, a heater 26 is provided on the end face of the filter 24 on the diesel engine lO side for igniting the particulates collected by the filter 24.

Note that foamed ceramic is used for the filter 24 on the Kinomio side, and the filter 24 has a three-dimensional network structure with a large number of elliptical holes communicating with each other.

The heater 26 on the Kimino side is connected to the electric heating fi 30-1 connected to the terminals 28-1 and 28-2 as shown in FIG.
．． 3o-2, 3o-3, 30-4゜30-5.30-6
．． It has 3o-7 and 3o-8. In addition, the heater 26
is grounded to the body of the vehicle.Ignition current is supplied to this heater 26 from the power circuit, and the power circuit is! ! In FIG. 01, the circuit is comprised of a circuit 32 and an ECU 34. The circuit 32 constitutes a main power supply circuit, and includes a switching transistor 38.4 that controls the output current of the battery 36.
The chopping operation is controlled by an ECU 34 mainly composed of a microcomputer.

Furthermore, in FIG. 1, an exhaust passage 42 is formed by enclosing the trap 20, and this exhaust passage 42 is provided with an exhaust flow rate regulating valve 44.

This exhaust flow rate: A joint 44 is driven to open and close by a diaphragm 46, and the diaphragm 46 has a vSV of 48.5
0. The vSV48 is connected to a vacuum pump (not shown), and the VSV50
is open to the atmosphere, and both are controlled by the ECU 34.

As described above, the ECU 34 includes the diesel engine 10, the heater 26. Although the exhaust flow rate control valve 44 is controlled,
Various detection signals are supplied to the ECU 34 to perform these controls.

In FIG. 1, the opening degree of the intake throttle valve 12 is determined by the opening degree sensor 5.
2, the diesel engine to+7) intake side pressure is detected by a pressure sensor 54, engine water temperature is detected by a temperature sensor 56, and engine load is detected by a load sensor 58.

Also, the rotation speed of the diesel engine 10 is detected by the rotation speed sensor 6.
0, the vehicle speed is detected by the vehicle speed sensor 62, and the oxygen concentration in the exhaust gas is detected by the 02 sensor 64.

Further, the temperature of the exhaust gas discharged from the diesel engine 10 to the trap 2° is detected by a temperature sensor 66, and the pressure thereof is detected by a pressure sensor 68. An operation sensor 72 detects whether or not a light control switch 70, which turns on and off the headlights, is operated.

The ECU 34 uses the above opening sensor 52. pressure sensor 54,
Temperature sensor 56, load sensor 58, rotation speed sensor 60.
Vehicle speed sensor 82.02 sensor 64, temperature sensor 66, pressure sensor 68. It is configured to be able to control the diesel engine IO based on various detection signals from the operation sensor 72, and to perform the following controls.

The ECU 34 can control the chopper circuit 32 so that the chopper circuit 32 supplies ignition current to the heater 26 when the pressure loss of the filter 24 exceeds a predetermined value.

In this case, this control is performed based on detection signals from a load sensor 58, a rotation speed sensor 60, and a pressure sensor 68.

The characteristic P shown in FIG. 3 is stored in the ROM of the ECU 34, and in the figure, the horizontal axis represents the detected engine rotational speed value N, and the vertical axis represents the detected engine load value. The ECU 34 uses the characteristic P from the detection signals of the load sensor 58 and the rotation speed sensor 60 to determine the exhaust pressure reference value PO, and when the detection value of the pressure sensor 68 exceeds this reference 4@PO, the chopper circuit 32 It is possible to control the chopper circuit 32 to supply ignition current to the heater 26.

Further, the ECU 34 can control the chopper circuit 32 to prohibit the supply of ignition current to the heater 26 until the trap 2o is warmed by exhaust gas, and to start supplying the ignition current for the first time when the trap 2o is warmed up.

Detection signals from the temperature sensor 66 and the temperature sensor 56 are used for this control, and the ECU 34 determines that when a predetermined time has elapsed after starting the diesel engine 1o, the temperature of the exhaust gas supplied to the playing card 2o has exceeded a predetermined value. When it is confirmed by the detection signal of the temperature sensor 66 that the temperature of the engine cooling water is higher than a predetermined value, it is determined that the trap 20 has warmed up, and the ignition current is supplied to the heater 26. You can control the start.

Note that when controlling the start of the ignition current to the heater 26,
The ECU 34 calculates the integrated value of the vehicle speed and the precision rL of the engine speed.
It can be confirmed in advance that the pressure sensor 68 does not malfunction when each value (for example, 200,000 rotations) exceeds a predetermined value.

The ECU 34 controls the flow rate of the exhaust gas flowing through the trap 20 by adjusting the opening degree of the exhaust flow rate control valve 44 so that the collected particulates ignited by the heater 26 are properly burned.

In addition, the ECU 34 can reduce the flow rate of the exhaust gas flowing through the trap 20 by adjusting the opening degree of the exhaust flow rate control valve 44 in response to the detection signals from the J02 sensor 64 and the temperature sensor 66, thereby preventing the trap 20 from melting.

Furthermore, the ECU 34 controls the value of the ignition current so that it becomes a value that correlates with the power supply voltage when the headlamp is turned on.

In this embodiment, since the output voltage of the battery 36 depends on the engine rotation speed, the value of the ignition current supplied to the heater 26 is controlled according to the detection signal of the rotation speed sensor 60, that is, the engine rotation speed. That is, when the engine speed is low, the duty ratio of the ignition current is decreased and its value is reduced, and when the engine speed is high, the duty ratio is increased and its (a) is increased. The value I of the ignition current is controlled by its duty ratio according to the characteristic 100 in FIG. 4. As a result, the peak voltage of the battery 36 is controlled to be substantially constant.

In addition, the ECU 34 controls the heater 26 when the headlamp is turned on.
The value of the ignition current can be gradually increased or decreased.

The ECU 34 of this embodiment detects the lighting state of the headlamp based on the detection signal of the operation sensor 72, and gradually controls the duty ratio of the ignition current to increase or decrease over time, as shown by characteristic 102 in the t55 diagram. ing. Further E
CU34 is electric heating 1li30-1,30-2.30-3.
30-4. The switching transistors 38 and 40 of the chopper circuit 32 can be duty-controlled so that the value is gradually decreased.

The present embodiment has the above configuration, and its operation will be explained below.

FIG. 6 shows a main routine explaining the entire process of the ECU 34, in which processes including a control process for the diesel engine 1O (step 2-00) and a regeneration process for the 1-lap 20 are repeatedly performed.

In step 200, the basic injection amount and injection timing of the fuel fuel 4 are first determined based on the amount of depression of the accelerator pedal, that is, the lever opening of the injection pump and the engine rotational speed. The basic injection amount and injection timing are corrected based on the engine coolant temperature, intake air temperature, etc., and the output of the diesel engine 10 is controlled using these corrections.

While the diesel engine 10 is operating, the exhaust flow rate adjustment jf,
44 is closed and the exhaust gas is guided to the trap 20 side, so that the particulates contained in the exhaust gas are removed from the filter 2.
4 is gradually collected in the filter 24 from the upstream surface toward the downstream direction, and is accumulated in the filter 24.

As a result, clean blades containing no particulates are discharged from the vehicle, thereby preventing any negative impact on the surrounding area.

In step 202, the process shown in FIG. 7 is first performed.

In the process shown in FIG. 7, it is determined whether a predetermined amount of particles have been collected by the filter 24 in the following manner.

In figure t57, the ECU 34 uses the characteristic P in figure t53 to determine the reference value PO from the detection signals of the load sensor 58 and rotation speed sensor 60 in order to determine whether the pressure loss of the filter 24 exceeds a predetermined value. Therefore, it is determined whether the detected value of the pressure sensor 68 exceeds this reference value PO (step 300).

At this time, when it is determined that the detected value of the pressure sensor 68 has exceeded the reference value PO, the pressure loss of the filter 24 has exceeded the predetermined value and a predetermined amount of 1'+R is extracted to the filter 24, and the diesel engine The loss of 10 mountain men has increased to a certain extent.

Next, the ECU 34 determines whether the rotation of the diesel engine 10, the integrated value, and the integrated vehicle speed each exceed set values (steps 302 and 304).

If it is determined in step 302 that the cumulative rotational speed of the diesel engine lO does not exceed the set value, the determination is made in step 300, and in step 304, the cumulative value of the vehicle speed is set, and if it is determined that the cumulative value does not exceed the set value, then step 300 is performed. 300 and 302 are each temporarily invalidated.

In step 306, the determinations in steps 300 and 302 that were once invalidated in steps 302 and 304 are examined. Note that it is preferable to omit steps 302, 304, and 306 when the reference value PO used in step 300 is not destroyed and there is no risk that the integrated values used in steps 302 and 304 will be volatile. It is also possible to perform only one of the steps .302 and 304 and omit the other steps.

In this way, when it is detected that a certain amount of particulates have accumulated in the filter 24, if the collection of particulates continues, the loss on the exhaust side will increase and the output of the diesel engine IO will decrease. The particulates collected by the filter 24 are ignited and burned by the heater 26 in the following manner.

In this device, the supply of ignition current to the heater 26 is inhibited until the i-wrap 20 is warmed up by the exhaust air, and only then started.

In FIG. 8, it is first confirmed that the exhaust system has been warmed up after a predetermined period of time has passed since the diesel engine 10 was started (step 400).

Then, the trap 20 receives tA from the diesel engine 10.
It is confirmed by the detection signal of the temperature sensor 66 that the temperature of the exhausted exhaust gas is higher than a predetermined temperature (step 40).
2).

Furthermore, the cooling water temperature of diesel engine 10 is 60℃ or higher.''
2 is confirmed by the detection signal of the temperature sensor 56 (step 404).

As described above, in this embodiment, it is determined that the trap 20 has been warmed when a predetermined period of time has elapsed since the diesel engine 10 started operating, the exhaust temperature has reached a predetermined temperature or higher, and the cooling water temperature has reached 60° C. or higher. is performed, and only after that, the ignition combustion process of the particulates captured by the filter 24 is started (step 40B).

Note that a temperature sensor that directly detects the temperature of the trap 20 or the temperature of the exhaust system may be provided, and the detection signal may be used to confirm that the trap 20 has been warmed.

As described above, in this embodiment, combustion of the particulates collected in the filter 24 is started after the trap 20 is warmed up, so thermal stress is prevented from occurring in the casing 22 and the filter 24, and Corruption is avoided.

Next, the process of step 406 will be explained.

In FIG. 9, the process of step 406 is performed by the filter 24
Process for controlling ignition of fine particles collected in (step 5)
00) and a process for adjusting and controlling the opening degree of the exhaust flow rate control valve 44 (step 502), and the image process is started at the same time.

FIG. 1O shows the ignition process at step 500, in which first, whether or not the headlamp is lit is determined based on the detection signal of the operation sensor 72 (step 600).

If it is determined that the headlamp is on, it is determined whether the rotation speed of the diesel engine lO is high or low based on the detection signal of the rotation speed sensor 60. When the rotation speed is 1100 Orp or more, it is determined to be high, and when it is less than 1100 Orp, it is determined to be low (
Step 602).

Furthermore, when it is determined in step 600 that the headlights are not lit, the duty ratio of the ignition current supplied to the heater 26 is set to a large value (step 60).
4) Also, when it is determined that the engine speed is high when the headlights are on, the duty ratio of the ignition current is set to a medium value (step 606), and it is determined that the engine speed is low when the headlights are on. When the duty ratio of the ignition current is set to a small value (step 608).

Thereafter, the supply of the ignition current with the duty ratio set as described above is started (steps 610 and 612).
).

Then, when the supply of the ignition current with the duty ratio set in step 608 is started, the duty ratio is gradually increased as shown in FIG.
Also each heating wire 30-1.30-2.30-3.30-4
．． 30-5.30-6.30-7.30-8 are fired in a predetermined order (step 614).

At this time, the ignition time of the heater 26 is monitored, and if it is determined that a predetermined time has elapsed (step 61
6), ignition of the heater 26 is terminated (step 608
), when the ignition of this heater 26 is completed, each heating wire 30
-1.30-2.30-3. 30-4. 30-5
, 3o-6, 30-7, and 30-8, the duty ratio of the ignition current supplied to the last heating wire 30 gradually decreases as shown in FIG. Reduced #111I11.

Next, the 1R control process performed in step 502 in FIG. 9 will be explained.

When the particulates collected by the filter 24 are ignited by the heater 26, the exhaust flow rate t provided in the exhaust passage 42
The iR moderation valve 44 is temporarily opened to allow most of the nozzle gas to flow into the exhaust path M42, thereby limiting the amount of exhaust gas flowing into the trap 20.

As a result, the flow velocity of the exhaust gas flowing into the trap 2o is reduced, and the particulates collected in the filter 24 are smoothly ignited and burned.

Further, under a predetermined exhaust temperature condition where the oxygen concentration in the exhaust becomes high, the exhaust flow rate ttttm valve 44 is forcibly opened.
be done. This control is performed for the following reason.

If high-load operation such as sudden uphill driving or high-speed driving is performed continuously with sufficient particulate matter collected in the filter 24, the emission %? 1 degree is a considerably high temperature, and the oxygen concentration in the exhaust gas is low because the amount of fuel injected is large.

If the accelerator pedal is opened or opened halfway during this high-load operation, the oxygen concentration in the exhaust gas will rapidly increase because a large amount of air is being supplied to the diesel engine IO.

Therefore, since a large amount of oxygen is supplied to a place where the exhaust gas temperature is considerably high, the ignited collected particles are rapidly combusted.

As a result, there is a risk that the filter 24 will become hot and the trap 20 will melt.

Therefore, in this embodiment, when the oxygen concentration in the exhaust gas increases under the exhaust temperature condition where the exhaust gas is at a considerably high temperature, the valve 44 is forcibly opened and the amount of exhaust gas flowing through the trap 20 is reduced. reduced. Note that the temperature of the exhaust gas is determined by the temperature sensor 6.
The oxygen concentration is detected from the detection signal of 02 sensor 64, and the oxygen concentration is detected from the detection signal of 02 sensor 64.

By performing the above-described ignition process (step 50o) and valve control process (step 502), first, the part of the particulates collected and accumulated in the filter 24 at the most upstream side of the exhaust gas is ignited.

Since the collected particulates are flammable and sufficient oxygen is contained in the exhaust gas, the ignited collected particulates serve as a ignition source, and the combustion of the collected particulates progresses toward the downstream of the exhaust gas.

When this combustion is completed, there is no residual phase of particulates in the filter 24, and as a result, the pressure loss in the trap 2o is reduced to the initial loss. That is, the trap 20 is regenerated and can be reused.

As explained above, according to this embodiment, when a predetermined amount of particles are accumulated in the filter 24 and the pressure loss thereof exceeds a predetermined value, the collected particles are ignited, and the amount of captured particles and the pressure loss are correspond almost exactly, so it is possible to perform regeneration processing of the trap 2o at an optimal time.

On the other hand, the trap 2
When the regeneration timing is determined, the amount of collected particles may vary due to differences in driving conditions, etc., and a large amount of particles may accumulate during the regeneration period. The temperature of the trap 20 rises abnormally. As a result, the trap 20 may be damaged or its durability may be reduced.

As described above, according to this embodiment, the trap 20 is activated at the optimal time.
Since the regeneration process is performed, it is possible to prevent damage to the trap 20 or improve its durability.

In this embodiment, the pressure loss was detected by the electrical pressure sensor 68, but a pipe line is formed between the upstream side and the downstream side of the trap 20, and the trap 20 is placed in the pipe line. Providing a mechanical switch such as a die size flam that is activated when the pressure difference between the upstream side and the downstream side reaches a predetermined value, and using this in place of the pressure sensor 68 can also reduce costs. It is suitable from the viewpoint of

Further, according to this embodiment, after it is confirmed that the trap 20 has warmed up, the particulates that have been drawn into the filter 24 are ignited, so that a large temperature difference is prevented from occurring in the playing card 20 portion. be done. Therefore, it is possible to avoid the inconvenience that the trap 20 and the like are damaged due to thermal stress caused by this temperature difference, and therefore, it is possible to improve the durability of the device.

Furthermore, according to this embodiment, when the trap 20 is regenerated when the headlamp is turned on, the battery 3
Since the ignition current with a duty ratio correlated to the output voltage of No. 6 is supplied to the heater 26, a decrease in illuminance of the headlamp can be prevented. Therefore, even if the regeneration process of the trap 20 is started while driving at night, good driving visibility is ensured, and therefore safe driving is possible.

Note that it is also preferable to configure the device so that a voltmeter is provided to detect the output voltage of the pantry 36 and the duty ratio of the ignition current is controlled in accordance with the detection signal.

According to this embodiment, when the trap 20 is regenerated when the headlamp is turned on and the ignition current to the heater 26 is suddenly increased or decreased, such as when the ignition current is turned on or off, the increase or decrease is done gradually. The supply voltage to the headlamp does not fluctuate suddenly, so
Even if the regeneration of the trap 20 starts or ends when the headlamp is turned on, flickering of the headlamp light is not visually recognized by the driver. Therefore, the driver does not feel anxious about the vehicle.

Further, according to the present embodiment, even if the oxygen concentration in the exhaust gas increases when the exhaust gas is under a predetermined exhaust temperature condition where the exhaust gas is at a high temperature, the valve 44 is forcibly opened and the exhaust gas flows to the trap 20. Since the amount of particles is limited, abnormal combustion of the particulates collected in the trap 20 can be prevented. For this reason, trap 2
0 can be prevented from melting and the reliability of the device can be improved.

[Effects of the Invention] As explained above, according to the present invention, the collected fine particles are ignited after it is confirmed that the trap has warmed up, so that it is possible to prevent a large temperature difference from occurring in the trap portion. Therefore, thermal stress caused by this temperature difference will not damage the trap or reduce its durability, and therefore it is possible to improve the reliability of the device.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the overall configuration of the device according to the present invention, Fig. 2 is an explanatory diagram of the configuration of the heater in the first cause, Fig. 3 is an explanatory diagram of the characteristics of the exhaust pressure reference value, and Fig. 4 is an illustration of the ignition current and its A characteristic diagram showing the relationship with the duty ratio. FIG. 5 is an explanatory diagram of the control characteristics of the duty ratio with respect to elapsed time. FIGS. It is a flowchart figure explaining control operation. lO...e diesel engine, 20-φ...trap. 24...Φ filter, 260...Heater, 32...Chopper circuit, 34...ECU. 56.661...Temperature sensor. Agent Patent Attorney Jun Nakataka

Claims (1)

[Claims] (1) A trap including a filter that abstracts particulates contained in engine exhaust gas and a heater that ignites the particulates collected by the filter, a temperature detection means that detects the temperature of the trap, and a temperature of the trap that is set to a predetermined value. 1. A particulate collection device comprising: a power supply circuit that starts supplying an ignition current to a heater when a value exceeds a certain value.